OBJECTIVES: To determine the long-range hazard, in terms of carcinogenesis, of radiotherapy and of chemotherapy used in treatment of Hodgkin's disease. SPECIFIC AIMS: (1) To determine the incidence of second primary malignancies in patients treated with modern modalities for primary Hodgkin's disease. (2) To determine the variation in incidence of second primary malignancies by modality of therapy for primary Hodgkin's disease, comparing: (a) non-intensive radiotherapy; (b) intensive radiotherapy; (c) non-intensive chemotherapy; (d) intensive chemotherapy. (3) To determine the variation in incidence of second primary malignancies by time since initiation of therapy for Hodgkin's disease. (4) To determine the distribution by organ site of second primary malignancies. METHODS: A cohort study is being conducted, using retrospective data on Hodgkin's disease patients diagnosed in 1940 to 1975 and followed to 1976 or death before 1976 and using prospective data on these same patients followed to 1980 and on patients newly diagnosed after 1975 and followed to 1980. It is planned to enroll 1000 patients diagnosed in 1940-69 and 1000 patients diagnosed in 1970-78. Patients with Hodgkin's disease are ascertained through registration records of four large cancer treatment centers.